qdns.h File Reference

headers of functions for DNS lookups More...

#include <netinet/in.h>

Go to the source code of this file.

Data Structures
struct	ips
	list of IP addresses for a given host More...

Macros
#define	FOREACH_STRUCT_IPS(_ptr, _s, _list)   for (_ptr = _list, _s = 0; _ptr != NULL; (_s < _ptr->count - 1) ? (_s++) : (_ptr = _ptr->next, _s = 0))
	iterate through all IP addresses in an list of MX entries More...
#define	INET_ADDRSTRLEN   16

Enumerations
enum	mx_special_priorities { MX_PRIORITY_IMPLICIT = 65536, MX_PRIORITY_USED = 65537, MX_PRIORITY_CURRENT = 65538 }
	values used as priority in struct ips to reflect special conditions More...
enum	dns_errors { DNS_ERROR_LOCAL = -1, DNS_ERROR_TEMP = -2, DNS_ERROR_PERM = -3 }
	error codes returned by the DNS lookup functions More...

Functions
int	ask_dnsmx (const char *, struct ips **)
	get info out of the DNS More...
int	ask_dnsaaaa (const char *, struct in6_addr **)
	get AAAA record from of the DNS More...
int	ask_dnsa (const char *, struct in6_addr **)
	get A record from of the DNS More...
int	ask_dnsname (const struct in6_addr *, char **)
	get host name for IP address More...
void	freeips (struct ips *)
int	domainvalid (const char *const)
void	sortmx (struct ips **p)
	sort MX list by priority More...
struct ips *	in6_to_ips (struct in6_addr *a, unsigned int cnt, const unsigned int priority)
	convert an array of in6_addr structs to a list of struct ips More...
static struct in6_addr	in_addr_to_v4mapped (const struct in_addr *ip4)
	convert an IPv4 address to a v4mapped IPv6 address More...
int	inet_pton_v4mapped (const char *str, struct in6_addr *addr)
	read an IPv4 address and convert it to a v4mapped IPv6 address More...

Detailed Description

headers of functions for DNS lookups

Macro Definition Documentation

#define FOREACH_STRUCT_IPS	(		_ptr,
			_s,
			_list
	)		for (_ptr = _list, _s = 0; _ptr != NULL; (_s < _ptr->count - 1) ? (_s++) : (_ptr = _ptr->next, _s = 0))

iterate through all IP addresses in an list of MX entries

Parameters

_ptr	struct ips* variable that holds the current entry
_s	unsigned short variable that holds the current index inside _ptr
_list	start point of the list to iterate over

Enumeration Type Documentation

enum dns_errors

error codes returned by the DNS lookup functions

Enumerator
DNS_ERROR_LOCAL	a local error during DNS lookup, errno is set
DNS_ERROR_TEMP	a temporary DNS error
DNS_ERROR_PERM	a permanent DNS error

enum mx_special_priorities

values used as priority in struct ips to reflect special conditions

Enumerator
MX_PRIORITY_IMPLICIT	used for implicit MX entries (i.e. A or AAAA)
MX_PRIORITY_USED	the entry has already been tried
MX_PRIORITY_CURRENT	used to mark the entry currently in use

Function Documentation

int ask_dnsa	(	const char *	name,
		struct in6_addr **	result
	)

get A record from of the DNS

Parameters

name	the name to look up
result	first element of a list of results will be placed, or NULL if only return code is of interest

Returns

if records have been found

Return values

0	no entries found
>0	how many entries were returned in result
DNS_ERROR_LOCAL	on error (errno is set)
DNS_ERROR_TEMP	temporary DNS error
DNS_ERROR_PERM	permanent DNS error

int ask_dnsaaaa	(	const char *	name,
		struct in6_addr **	result
	)

get AAAA record from of the DNS

Parameters

name	the name to look up
result	first element of a list of results will be placed

Return values

0	no entries found
>0	how many entries were returned in result
DNS_ERROR_TEMP	if temporary DNS error
DNS_ERROR_PERM	if permanent DNS error
DNS_ERROR_LOCAL	on error (errno is set)

int ask_dnsmx	(	const char *	name,
		struct ips **	result
	)

get info out of the DNS

Parameters

name	the name to look up
result	first element of a list of results will be placed

Return values

0	on success
1	if host is not existent
DNS_ERROR_TEMP	if temporary DNS error
DNS_ERROR_PERM	if permanent DNS error
DNS_ERROR_LOCAL	on error (errno is set)

int ask_dnsname	(	const struct in6_addr *	ip,
		char **	result
	)

get host name for IP address

Parameters

ip	the IP to look up
result	name will be stored here

Returns

how many names were found, negative on error

Return values

0	host not found
DNS_ERROR_LOCAL	local error (errno is set)
DNS_ERROR_TEMP	temporary DNS error
DNS_ERROR_PERM	permanent DNS error

int domainvalid

(

const char *const

host

)

check if a string is a valid fqdn

Parameters

host	the name to check

Returns

if the string is a valid domain name

Return values

0	everything is ok
1	on syntax error

if there is a standard function doing the same throw this one away

void freeips

(

struct ips *

p

)

free memory of IP list

Parameters

p	IP list to free

struct ips* in6_to_ips	(	struct in6_addr *	a,
		unsigned int	cnt,
		const unsigned int	priority
	)

convert an array of in6_addr structs to a list of struct ips

Parameters

a	the input array
cnt	the address count in a (must be >0)
priority	priority of the new records

Returns

list of struct ips

Return values

NULL	an allocation error happened during conversion

a will always be freed.

static struct in6_addr in_addr_to_v4mapped ( const struct in_addr *  ip4 )

static

convert an IPv4 address to a v4mapped IPv6 address

Parameters

ip4	the address to convert

Returns

the v4mapped address

Warning

This does not handle any special addresses specifically.

int inet_pton_v4mapped	(	const char *	str,
		struct in6_addr *	addr
	)

read an IPv4 address and convert it to a v4mapped IPv6 address

Parameters

str	the string to read in
addr	where to store the resulting address

Returns

the same values as inet_pton()

Return values

1	address was successfully read in

void sortmx

(

struct ips **

p

)

sort MX list by priority

Parameters

p	list of MX entries

Inside each entry of p the IPv6 entries are moved to the front so that IPv6 addresses are prefered. If 2 entries of p have the same priority those that contain IPv6 addresses will be moved to the front for the same reason.

If IPV4ONLY is defined all IPv6 addresses will be stripped from the list.